双歧杆菌对坏死性小肠结肠炎新生大鼠肠道β-防御素-2表达的影响

目的 探讨双歧杆菌对坏死性小肠结肠炎（NEC）新生大鼠肠道β-防御素-2（BD-2）表达的影响。方法 将40只大鼠分为正常对照组、双歧杆菌对照组、NEC模型组和双歧杆菌干预组（n=10）。采用缺氧+冷刺激+人工喂养的方法建立NEC模型。双歧杆菌对照组和双歧杆菌干预组在每日冷刺激后经胃管注入双歧杆菌，每天1次，连续3 d。收集各组大鼠末段回肠组织于光镜下观察形态学改变并对肠道损伤进行评分，采用免疫组织化学法、qRT-PCR法分别检测各组大鼠回肠黏膜组织中BD-2蛋白及mRNA的表达水平。结果 NEC模型组肠道损伤评分分别高于正常对照组、双歧杆菌对照组、双歧杆菌干预组（P < 0.05）；双歧杆菌干预组的肠道损伤评分高于正常对照组和双歧杆菌对照组（P < 0.05）。正常对照组BD-2 mRNA及蛋白的表达低于双歧杆菌对照组、NEC模型组和双歧杆菌干预组（P < 0.05）；双歧杆菌对照组BD-2 mRNA及蛋白的表达高于NEC模型组和双歧杆菌干预组（P < 0.05）；双歧杆菌干预组BD-2 mRNA及蛋白的表达高于NEC模型组（P < 0.05）。结论 双歧杆菌可诱导大鼠肠道表达BD-2，其可能通过增加BD-2的表达而减轻肠道炎症反应，发挥对新生大鼠NEC模型的保护作用。

Effect of Bifidobacterium on the expression of β-defensin-2 in intestinal tissue of neonatal rats with necrotizing enterocolitis

Objective To study the effect of Bifidobacterium on the expression of β-defensin-2 (BD-2) in intestinal tissue of neonatal rats with necrotizing enterocolitis (NEC). Methods A total of 40 rats were randomly divided into four groups:normal control, Bifidobacterium control, NEC model, and Bifidobacterium treatment, with 10 rats in each group. A rat model of NEC was induced by hypoxia, cold stimulation, and artificial feeding. The rats in the Bifidobacterium control and Bifidobacterium treatment groups were given Bifidobacterium via the gastric tube after cold stimulation once a day for three consecutive days. The morphological changes of the terminal ileum were observed under a light microscope and the intestinal injury score was determined. Immunohistochemistry and qRT-PCR were used to measure the protein and mRNA expression of BD-2 in the ileal mucosal tissue. Results The NEC model group had a significantly higher intestinal injury score than the normal control, Bifidobacterium control, and Bifidobacterium treatment groups (P < 0.05). The Bifidobacterium treatment group had a significantly higher intestinal injury score than the normal control and Bifidobacterium control groups (P < 0.05). The mRNA and protein expression of BD-2 in the normal control group was significantly lower than in the Bifidobacterium control, NEC model, and Bifidobacterium treatment groups (P < 0.05). The Bifidobacterium control group had significantly higher mRNA and protein expression of BD-2 than the NEC model and Bifidobacterium treatment groups (P < 0.05). The Bifidobacterium treatment group had significantly higher mRNA and protein expression of BD-2 than the NEC model group (P < 0.05). Conclusions Bifidobacterium can induce the expression of BD-2 in intestinal tissue of rats and reduce inflammatory response by increasing the expression of BD-2. This provides a protective effect on neonatal rats with NEC.